Hello and hope you are doing well.
As suggested it could be due to atherosclerosis. Blood vessels are narrowed most commonly due to atherosclerosis, a disease where the 'fatty' material in the blood gets deposited in the walls of the blood vessels. Certain conditions such as diabetes, high blood pressure, smoking and sedentary life style promote this. Sometimes the damaged vessel may develop a clot at the site of injury. When a blood clot tries to pass through a narrowed lumen it causes an obstruction to flow.
The treatment is aimed at the cause. Controlling diabetes and hypertension and following good lifestyle measures can help control disease process. Regular exercise and avoiding fatty foods can help to increase the flow through the narrowed arteries. But beyond a certain level of obstruction, it may need surgical correction.
Hope this helped and do keep us posted.
Well, stenosis simply means 'narrowing' and there can be several reasons for a narrowing. I am going to assume you are referring to atherosclerosis here? and I have to say there is unfortunately no current medications which remove the plaque from arteries.